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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 907 · 40 questions
TalentJR

The trick (Seventh times eleven): A leapfrog list: start with two numbers, then each number is the sum of the two before it, up to 10 numbers. Find the 7th number. Multiply it by 11 (the number with a 0 on the end, plus the number): that is the total of all 10.

NameDateTime takenScore ___ / 40
  1. 1.A leapfrog list starts 6, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  2. 2.2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 =
  3. 3.A leapfrog list starts 7, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  4. 4.5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 + 309 =
  5. 5.Leapfrog list (each number is the sum of the two before it): 1, 8, 9, 17, 26, 43, 69, 112, 181, 293. What is 11 × the 7th number?
  6. 6.2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 =
  7. 7.4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 + 322 =
  8. 8.Leapfrog list (each number is the sum of the two before it): 9, 3, 12, 15, 27, 42, 69, 111, 180, 291. What is 11 × the 7th number?
  9. 9.7 + 3 + 10 + 13 + 23 + 36 + 59 + 95 + 154 + 249 =
  10. 10.A leapfrog list starts 6, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  11. 11.Leapfrog list (each number is the sum of the two before it): 5, 8, 13, 21, 34, 55, 89, 144, 233, 377. What is 11 × the 7th number?
  12. 12.Leapfrog list (each number is the sum of the two before it): 7, 7, 14, 21, 35, 56, 91, 147, 238, 385. What is 11 × the 7th number?
  13. 13.Leapfrog list (each number is the sum of the two before it): 1, 6, 7, 13, 20, 33, 53, 86, 139, 225. What is 11 × the 7th number?
  14. 14.3 + 2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 =
  15. 15.Leapfrog list (each number is the sum of the two before it): 7, 4, 11, 15, 26, 41, 67, 108, 175, 283. What is 11 × the 7th number?
  16. 16.2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 =
  17. 17.4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 =
  18. 18.A leapfrog list starts 9, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  19. 19.5 + 3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 =
  20. 20.A leapfrog list starts 9, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  21. 21.4 + 2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 =
  22. 22.A leapfrog list starts 3, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  23. 23.3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 + 369 =
  24. 24.Leapfrog list (each number is the sum of the two before it): 8, 5, 13, 18, 31, 49, 80, 129, 209, 338. What is 11 × the 7th number?
  25. 25.A leapfrog list starts 7, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  26. 26.8 + 7 + 15 + 22 + 37 + 59 + 96 + 155 + 251 + 406 =
  27. 27.1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 =
  28. 28.7 + 1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 =
  29. 29.Leapfrog list (each number is the sum of the two before it): 9, 6, 15, 21, 36, 57, 93, 150, 243, 393. What is 11 × the 7th number?
  30. 30.A leapfrog list starts 7, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  31. 31.A leapfrog list starts 5, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  32. 32.Leapfrog list (each number is the sum of the two before it): 9, 2, 11, 13, 24, 37, 61, 98, 159, 257. What is 11 × the 7th number?
  33. 33.3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 =
  34. 34.A leapfrog list starts 4, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  35. 35.Leapfrog list (each number is the sum of the two before it): 6, 6, 12, 18, 30, 48, 78, 126, 204, 330. What is 11 × the 7th number?
  36. 36.Leapfrog list (each number is the sum of the two before it): 5, 2, 7, 9, 16, 25, 41, 66, 107, 173. What is 11 × the 7th number?
  37. 37.Leapfrog list (each number is the sum of the two before it): 3, 1, 4, 5, 9, 14, 23, 37, 60, 97. What is 11 × the 7th number?
  38. 38.8 + 3 + 11 + 14 + 25 + 39 + 64 + 103 + 167 + 270 =
  39. 39.8 + 8 + 16 + 24 + 40 + 64 + 104 + 168 + 272 + 440 =
  40. 40.Leapfrog list (each number is the sum of the two before it): 2, 4, 6, 10, 16, 26, 42, 68, 110, 178. What is 11 × the 7th number?

Answer key

  1. 506
  2. 726
  3. 1001
  4. 803
  5. 759
  6. 638
  7. 836
  8. 759
  9. 649
  10. 418
  11. 979
  12. 1001
  13. 583
  14. 341
  15. 737
  16. 550
  17. 660
  18. 759
  19. 539
  20. 935
  21. 396
  22. 341
  23. 957
  24. 880
  25. 649
  26. 1056
  27. 671
  28. 473
  29. 1023
  30. 561
  31. 979
  32. 671
  33. 693
  34. 924
  35. 858
  36. 451
  37. 253
  38. 704
  39. 1144
  40. 462

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